The advent of fuel cells as alternative propulsion systems or auxiliary power units (APU's) for automotive and other applications, and the advent of advanced engines having capability for lower emissions and better fuel efficiency, have created a need for improved and highly specialized gas flow control valves. This includes diesel fuel reformate valves which may be used with APU fuel cells for example, or to provide NOx reductants for emissions control in advanced diesel engines, or for other uses. A reformer or fuel processor, can convert a hydrocarbon fuel (e.g., methane, propane, natural gas, gasoline, diesel, oxygenated hydrocarbons, and the like) to hydrogen or to a less complex hydrocarbon. More particularly, fuel reforming can comprise mixing a hydrocarbon fuel with air, water, and/or steam in a mixing zone of the reformer prior to entering a reforming zone of the reformer, and converting the hydrocarbon fuel into, for example, hydrogen (H2), byproducts, e.g., carbon monoxide (CO), methane (CH4), inert materials e.g., nitrogen (N2), carbon dioxide (CO2), and water (H2O). Also, fuel cells for example are known to use hydrogen gas as an energetic fuel for exothermic combination with oxygen at high temperature. Hydrogen may be supplied continuously to a fuel cell as a “reformate” product. Additionally, regarding emissions technology, Hydrogen reformate may need to be directed to a Diesel Particulate Filter (DPF), NOx trap, or other device.
U.S. Pat. No. 4,337,742 shows an idle air control valve that is similar to the idle air control valve found in many modern engines. However, this single valve design has several disadvantages, some of which become acutely apparent when the valve is sized to meet the airflow requirements of a fuel reformer application or an application requiring higher flow than that dictated for an internal combustion engine. For example, if a single valve of this valve design was used for a reformer application or for a high flow application, it would have poor resolution when low airflow is required.
U.S. Patent application to Gagnon, US 2002/0017322, discloses an air control valve for fuel cells. The device has a single air inlet that enters a manifold. The manifold houses two valves, and each valve has its own respective outlet. Since each valve has its own outlet and its own airflow or airmass meter, the resultant airflow total resolution is not controlled as a whole. Rather, separate and distinct sections of the device are controlled to control the total airflow.
Thus, what is needed in the art is a valve that can control the flow of gases or liquids with a high degree of resolution without necessitating use of multiple apertures and multiple actuator motors. In a present embodiment, increased flow and resolution capability is provided by adding a second valve and a second stage. Additionally, only one motor is necessary to actuate the actuator.